In the known method, the materials to be treated are fed through a slit-type space which is bounded by the interior surface of a cylindrical external jacket and the exterior surface of a rotor rotating concentrically inside the jacket, the common axis of the jacket and the rotor extending horizontally. The rotor is caused to rotate in order to convey the material to be treated through the relatively narrow slit-type gap, ribs or upright studs or pins extending along a helix also preferably being provided on the exterior surface of the rotor.
The disadvantage of the known method is, firstly, that it is not possible or very difficult to ensure that the slit-type gap is always completely filled with the material to be treated, and secondly the conveyance through the slit-type gap proceeds very laboriously, as a result of which the efficiency of the method leaves something to be desired.
The object of the invention is to provide an improved method.